gymnasium

n.

1590s, "place of exercise," from Latin gymnasium "school for gymnastics," from Greek gymnasion "public place where athletic exercises are practiced; gymnastics school," in plural, "bodily exercises," from gymnazein "to exercise or train," literally or figuratively, literally "to train naked," from gymnos "naked" (see naked). Introduced to German 15c. as a name for "high school" (more or less paralleling a sense in Latin); in English it has remained purely athletic.